Positive-air-pressure machine conduit

ABSTRACT

A conduit for delivering a supply of gas under a positive pressure includes a conduit wall having a first conduit end and a second conduit end. The first conduit end is adapted to be attached to the supply of gas. The conduit wall is deformable between (a) an open condition in which the conduit wall defines a conduit passage along which the supply of gas can travel between the first conduit end to the second conduit end, and (b) a collapsed condition in which the conduit wall substantially collapses the conduit passage.

CROSS-REFERENCE TO APPLICATIONS

This application is a continuation of U.S. application Ser. No. 17/178,388, filed Feb. 18, 2021, which is a continuation of U.S. application Ser. No. 16/899,712, filed Jun. 12, 2020, which is a continuation of U.S. application Ser. No. 16/386,518, filed Apr. 17, 2019, which is a continuation of U.S. application Ser. No. 16/006,209, filed Jun. 12, 2018, which is a divisional application of U.S. application Ser. No. 15/607,224, filed May 26, 2017, now U.S. Pat. No. 10,029,062, which is a continuation of U.S. application Ser. No. 11/578,293, filed Oct. 13, 2006, now abandoned, which is the US national phase of international application PCT/AU2005/000539 filed Apr. 15, 2005, which designated the U.S. and claimed the benefit of AU 2004902020 filed Apr. 15, 2004, the entire contents of each of which are hereby incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a positive-air-pressure (PAP) machine conduit. The present invention also relates to headgear including such a conduit and to nose pieces including such a conduit.

BACKGROUND OF THE INVENTION

One of the main factors influencing the success or failure of a patient to adopt a CPAP apparatus used in the treatment of obstructive sleep apnea is the patient's ability to handle the discomfort of the headgear and supply conduit associated with such apparatus.

Such apparatus can tend to limit a patient's ability to move or roll during sleep, thus adding to the potential discomfort for a patient.

Therefore, a need has developed in the art to overcome or ameliorate at least some of the disadvantages of such apparatus, or to provide a useful alternative.

SUMMARY OF THE INVENTION

One aspect of the invention relates to a conduit for delivering a supply of gas under a positive pressure. The conduit includes a conduit wall having a first conduit end and a second conduit end. The first conduit end is adapted to be attached to the supply of gas. The conduit wall is deformable between (a) an open condition in which the conduit wall defines a conduit passage along which the supply of gas can travel between the first conduit end to the second conduit end, and (b) a collapsed condition in which the conduit wall substantially collapses the conduit passage.

Another aspect of the invention relates to headgear for delivering a supply of gas under a positive pressure to a patient. The headgear includes a connector adapted to be attached to the supply of gas. A pair of side portions are adapted to extend along opposite sides of the patient's head. Each of the side portions defines a conduit having a first conduit end attached to the connector and a second conduit end adapted to be positioned adjacent the patient's nose. A head attachment structure is adapted to releasably secure the headgear to the patient's head.

Another aspect of the invention relates to a nasal assembly for delivering a supply of gas under a positive pressure to a patient. The nasal assembly includes a connector adapted to be attached to the supply of gas, a nose-piece adapted to engage the patient's nose, and a pair of side portions adapted to extend along opposite sides of the patient's head. Each of the side portions defines a conduit having a first conduit end attached to the connector and a second conduit end adapted to connect to the nose-piece. A head attachment structure is adapted to releasably secure the headgear to the patient's head.

Another aspect of the invention relates to a method for using a conduit to deliver a supply of gas under a positive pressure. The method includes providing a conduit including a conduit wall having a first conduit end and a second conduit end. The conduit wall is deformable between (a) an open condition in which the conduit wall defines a conduit passage along which the supply of gas can travel between the first conduit end to the second conduit end, and (b) a collapsed condition in which the conduit wall substantially collapses the conduit passage. The method includes connecting the first conduit end of the conduit to the supply of gas, delivering the supply of gas into the conduit via the first conduit end such that the supply of gas urges the conduit wall into the open condition to allow the supply of gas to travel from the first conduit end to the second conduit end, and disposing the second conduit end of the conduit at a position at which the supply of gas is to be delivered.

Another aspect of the invention relates to a method for constructing headgear that delivers a supply of gas under a positive pressure to a patient. The method includes providing headgear including at least one conduit that defines a conduit passage along which the supply of gas can travel, mapping the shape of a particular patient's head, and forming the headgear into a headgear shape in accordance with the mapping such that the headgear achieves a substantially close and comfortable fit on the particular patient's head.

Another aspect of the invention relates to a positive-air-pressure (PAP) machine conduit. The conduit includes flexible conduit walls, a first conduit end adapted for attachment to a supply of gas under a positive pressure, and a second conduit end. The conduit is configured such that when the first end is connected to the supply, the gas urges the conduit walls into a first condition in which the walls define a conduit passage along which the gas travels from the first end to the second end. The conduit is deformable into a second condition in which the passage is substantially collapsed.

In an embodiment, the conduit may be formed from a single piece of sheet material.

In another embodiment, the conduit may be formed from at least two pieces of sheet material which are joined together.

In another embodiment, the conduit may be formed from woven sheet material. In yet another embodiment, the conduit may be formed from flexible polymeric sheet material, which in an embodiment may be an elastic material.

In another embodiment, the material may a lamination of a plurality of materials. In forms of this embodiment, the material may be a lamination of a thin foam layer and a fabric layer which, in one form, is coated on the foam layer, or felt flocking which, in one form, is coated on the foam layer. Such embodiments may provide a soft, warm comfortable feel against the skin of a patient using the conduit.

In another embodiment, parts of the conduit which are adapted to be in contact with the skin of a patient may be of gel-like material.

In yet another embodiment, the conduit walls may be configured to permit the leaking of gas therethrough from the passage.

In yet another embodiment, the conduit walls may include wall portions in the form of double walls defining a substantially gas tight space between them.

In still another embodiment, the conduit walls may be substantially devoid of elasticity. In another embodiment, the conduit walls may have elasticity so as to be expandable. In yet further embodiments, the conduit walls may have at least one region with elasticity and at least one other region substantially devoid of elasticity, and/or different regions of differing amounts of elasticity.

Another aspect of the invention relates to a positive-air-pressure (PAP) headgear. The headgear includes connection means for connection in fluid-flow communication to a supply of gas configured for providing gas under a positive pressure and a pair of conduits according to above-noted aspects of the invention or embodiments thereof. The conduits are configured to extend around opposite sides of a patient's head. The first end of each conduit is connected in fluid-flow communication to the connection means and the second end of each conduit is configured, when the headgear is being worn by the patient, to be positioned adjacent the patient's nose. Head attachment means releasably secures the headgear to the patient's head.

In an embodiment, the second end may be configured to be connected to a nose-piece for directing gas that has passed along the passages from the second ends to within the patient's nose.

In another embodiment, the headgear may be configured, when the headgear is being worn by the patient, for the conduits to extend across the patient's nose. The headgear may define a pair of apertures opening into the conduits and positioned to be adjacent the patient's nose for attachment of at least one nose-piece for directing gas that has passed along the passages to within the patient's nose.

In this case, in one embodiment, the second ends may be integrally joined to each other.

Also in this case, the headgear may be provided with a pair of seal rings, each joined to the headgear at a respective aperture for establishing a close seal with the at least one nose-piece.

In another embodiment, the material from which each conduit is formed may be adapted to permit the passage of water vapour therethrough to enhance patient comfort particularly in a warm climate, but is substantially air tight.

In another embodiment, the head attachment means may include a strap joined to at least one of the pair of conduits.

In another embodiment, the pair of conduits and at least part of the connection means may be integral with one another in a unitary construction.

In another embodiment, the pair of conduits, at least part of the connection means, and the strap are integral with one another in a unitary construction.

In yet another embodiment, the headgear may be configured such that the strap extends around a portion of the head posterior to the apex.

In yet another embodiment, the headgear may be configured such that, when the headgear is being worn by the patient, the connection means may be disposed at a position adjacent to or anterior of the apex of the patient's head.

In an embodiment, the headgear may be configured such that, when the connection means is connected in fluid-flow communication to a supply of gas with the supply of gas providing gas under a positive pressure so that the gas travels along the pair of conduits, collapsing of the passage of one of the conduits due to compression being applied to that conduit, which collapsing results in a decrease in the volume flow rate of gas through that passage, results in a deformation of the passage of the other conduit and an associated increase in volume flow rate of gas through the passage of that other conduit.

The headgear may be configured such that, as a result of the deformation of the passage of the other conduit, the total volume flow rate of the gas through the pair of conduits remains substantially constant during the collapsing of the passage of the one conduit.

In an embodiment, the collapsing of the passage of the one conduit is deformation which causes a change in the ratio between a height extent and a lateral extent of that passage. In one embodiment, the height extent decreases and the lateral extent increases. Similarly, in another embodiment, the deformation of the passage of the other conduit is deformation which causes a change in the ratio between a height extent and a lateral extent of that passage. In one embodiment, the height extent increases and the lateral extent decreases.

In another embodiment, the headgear may include an adjustable head cap with the conduits being attached to the cap at opposite sides thereof. In this case, the cap may constitute the attachment means, and the connection means may be mounted on the cap.

In yet another embodiment, the conduits may be detachable from the attachment means so that the attachment means may be selectively releasably connected with differently sized and/or shaped conduits. In this case, the conduits may be selectively releasably connected with differently sized and/or shaped attachment means, whereby the headgear may form part of a modular headgear system having interchangeable attachment means and conduits.

In an embodiment, the headgear may be adapted for use with a patient mask configured to fit the patient's head adjacent the patient's nose to direct gas from the conduits to the nose. Then, the headgear may be adapted to be detachable from the mask to enable the patient to selectively remove the mask from the headgear and hence from the patient's head while the headgear continues to be being worn by the patient.

Yet another aspect of the invention relates to a nose-piece configured for attachment to a headgear, according to above-noted aspects of the invention or embodiments thereof, for directing air from the second end of a conduit to the interior of the patient's nose.

In an embodiment, the nose-piece may include a conduit according to above-noted aspects of the invention or embodiments thereof.

In another embodiment, the flexible conduit walls may be double walls defining a substantially gas-tight space between them.

In another embodiment, the nose-piece may include a nozzle opening into the space to enable the delivery of gas into the space to inflate the nose-piece.

In another embodiment, the nose-piece may be a conduit according to above-noted aspects of the invention or embodiments thereof.

In another embodiment, the nose-piece may include a pair of nostril formations for being received in a patient's nose and for directing gas from the conduit passage into the nose. Then, in an embodiment, the conduit may define a pair of nostril formation apertures, each nostril formation extending through a respective nostril formation aperture.

In another embodiment, the nostril formations may be customized to closely fit the nostrils of a particular patient.

In yet another embodiment, parts of the headgear which are adapted to be in contact with the skin of a patient may be of gel-like material.

Still another aspect of the invention relates to a method of using a PAP machine conduit, according to above-noted aspects of the invention or embodiments thereof, for delivering air. The method includes connecting the first end of the conduit to a supply means configured for supplying air under a positive pressure, delivering air by the machine to the conduit via the first end such that the air urges the conduit walls into the first condition, and disposing the second end at a position at which the air is to be delivered such that the air that has passed along the passage exits the conduit at the second end.

Still another aspect of the invention relates to a method of providing a PAP headgear for use by a particular patient. The headgear includes connection means for connection in fluid-flow communication to a supply of gas configured for providing gas under a positive pressure, a pair of conduits configured to extend around opposite sides of the particular patient's head, and head attachment means to releasably secure the headgear to the particular patient's head. Each conduit has flexible conduit walls, a first conduit end connected in fluid-flow communication to the connection means, and a second conduit end configured, when the headgear is being worn by the particular patient, to be positioned adjacent the particular patient's nose. Each conduit is configured such that when the connection means is connected to the supply, the gas urges the conduit walls into a first condition in which the walls define a respective conduit passage along which the gas travels from the respective first end to the respective second end and wherein each conduit is compressibly deformable into a second condition in which the passage is substantially collapsed. The method includes mapping the shape of the particular patient's head, and forming the headgear into a headgear shape in accordance with the mapping such that the headgear, when fitted to the particular patient's head, is a close fit thereon.

In an embodiment, the method may include after mapping the shape of the particular patient's head, forming a head template in accordance with the mapping. Also, the forming the headgear into a headgear shape may include forming the headgear in accordance with the shape of the template.

In another embodiment, the mapping the shape of the particular patient's head may be carried out manually, while in another embodiment, the mapping the shape of the particular patient's head may be carried out by mapping means which are at least partially automated.

When the mapping the shape of the particular patient's head is carried out by mapping means which are at least partially automated, the mapping means may include a computer.

When the mapping the shape of the particular patient's head is carried out by mapping means which are at least partially automated, the mapping the shape of the patient's head may include touchless sensing of the shape of the patient's head. The touchless sensing may involve the use of a camera or a laser sensor.

In an embodiment, the headgear may be a type of headgear having at least two pieces of sheet material which are joined together, wherein the forming the headgear into a headgear shape in accordance with the mapping includes forming each of the pieces into a respective sheet shape configured to enable the achievement of the headgear shape when the headgear is formed, and joining the pieces of sheet material together in the forming of the headgear.

In another embodiment, the joining the pieces of sheet material together in the forming of the headgear includes joining the pieces of sheet material along predetermined joint paths to define detachment areas adjacent the joint paths in which the pieces of sheet material are detached from each other.

The joint paths may constitute lines of fold lines to facilitate curving of the joined pieces of sheet material in the forming of the headgear into the headgear shape.

Each joint path may be of a zig-zag configuration, and may be substantially sinusoidal so as to define peaks and troughs.

In this case, adjacent pairs of the joint paths may be positioned relative to each other so that each peak of one joint path of the pair is aligned with a respective trough of the other joint path and vice versa, whereby the detachment areas may be substantially diamond-shaped.

Other aspects, features, and advantages of this invention will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, which are a part of this disclosure and which illustrate, by way of example, principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings facilitate an understanding of the various embodiments of this invention. In such drawings:

FIG. 1 is a perspective view of a headgear according to an embodiment of the invention, the headgear in a position of use;

FIG. 2 is a plan view of the headgear of FIG. 1 shown in a flattened-out condition (i.e., not in a position of use);

FIG. 3 is a perspective view of another embodiment of the headgear viewed from another angle to that shown in FIG. 1;

FIG. 4 is a perspective view, shown partly in cross-section, of a nose piece according to an embodiment of the invention;

FIG. 5 is schematic plan view of a nose piece according to another embodiment of the invention;

FIG. 6 is a schematic elevation of a conduit according to an embodiment of the invention, the conduit shown attached to an air supply;

FIG. 7 is a schematic perspective view of a cushion indicative of a manner of forming a headgear according to an embodiment of the invention;

FIG. 8 is a schematic elevation of the cushion of FIG. 7 in a formed condition;

FIG. 9 is a one way inflation nipple;

FIG. 9A is cross section through a portion of the nipple of FIG. 9;

FIG. 10 is a perspective view of a tube structure for connecting a headgear to an air supply pipe;

FIG. 11 is a plan view of headgear similar to that of FIGS. 1 and 2, showing a strap system included with the headgear; and

FIG. 12 is a plan view of headgear similar to that of FIGS. 1 and 2, showing a collapsible cuff included on the ends of the conduits of the headgear.

DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS

Referring to FIGS. 1 and 2, there is shown a patient interface including a headgear 10 according to an embodiment of the invention. The headgear 10 includes a pair of conduits or side portions 12 which are joined integrally to each other by a central portion 14 via joints. A head attachment means in the form of a strap 16 is also joined integrally to the side portions 12 as shown in FIG. 1, so that the side portions 12, central portion 14, and strap 16 are all of an integral, unitary construction.

The side portions 12, central portion 14 and strap 16 are formed by joining together, e.g., by high-frequency (HF) plastics welding, a pair of polymeric (e.g., plastic) sheets 17. The manner in which the sheets 17 are joined together is such that the middle portions of the sheets 17 can be parted from each other to define passages running along the length of the side portions 12, as described in more detail below. It will be appreciated that, when the sheets 17 are configured to form such passages in the side portions 12, the side portions 12 constitute conduits, and will be referred to as such below. The sheets 17 may be joined together in any suitable manner to form such passages in the side portions 12.

The conduits 12, at the positions where the sheets 17 are joined together (e.g., by plastics welding), may be provided with inwardly extending pleats (e.g., V-shaped recesses extending inwardly with respect to the conduits) to facilitate the parting of the middle portions of the sheets 17 and hence the formation of the passages, as referred to above.

The central portion 14 has an aperture 18 at the center thereof. The headgear 10 includes a T-connection or T-shaped connector 20 which extends into the aperture 18. The T-connection 20 includes a pair of side pipes 22 and a central pipe 24 which opens into the side pipes 22. The side pipes 22 extend, in opposite directions, between the plastic sheets 17, with the center pipe 24 protruding from the central portion 14 via the aperture 18. The side pipes 22 are firmly engaged with the plastic sheets 17 so as to form a substantially air-tight seal with the sheets 17, while permitting sonic rotational movement along the joints between the side pipes 22 and the sheets 17.

The positions of the ends 26 of the side pipes 22 (indicated in broken lines in FIGS. 1 and 2) also serve to mark the transition from the central portion 14 to the respective side portions 12. Accordingly, the positions of the conduits 12 corresponding to the ends 26 of the side pipes 22 constitute first upper ends 28 of the conduits 12.

An attachment formation or swivel 30 which has a cylindrical union 32 at its end, is mounted around the center pipe 24 so as to be rotatable relative to the center pipe 24. As discussed further below, the attachment formation 30 is for receiving the end (not shown) of an air supply pipe leading from a flow generator or an air supply means (also not shown) for supplying air under pressure to the headgear 10, so as to connect the air supply pipe in fluid-flow communication with the center pipe 24 while permitting rotation of the air supply pipe.

In FIGS. 1 and 3, the headgear 10 is shown mounted on a patient's head 34. As illustrated, the central portion 14 and T-connection 20 of the headgear 10 are configured to extend across the patient's head 34 at a position somewhat anterior of the apex 36 of the head 34, while the strap 16 is configured to extend around the portion of the head 34 posterior of the apex 36. The headgear 10 is designed to conform to the curvature of the occiput of the patient's head 34 so that the headgear 10 is stably seated thereon.

Also, as can be seen in FIGS. 1 and 3, the conduits 12 extend downwards on opposite sides of the patient's head 34 between the eye and ear 38 of the patient on each side of the head 34. The conduits 12 curve forwards towards their lower extremities, to terminate at second ends 40 (see FIG. 1) that are opposite to the first ends 28. The second ends 40 are adjacent to the patient's nose 42 and may be attached to a nasal interface or seal forming portion, such as the nose piece 150 referred to below (see FIG. 3) which is in contact with the patient's nose.

As shown in FIG. 1, attached to the second end 40 of each conduit 12 is a nose attachment formation or nasal/seal interface connector 44, having a part which extends via the respective second end 40, between the plastic sheets 17, to a position (not shown) within the conduit 12, and another portion 46 which is outside the conduit 12.

Each portion 46 of the nose attachment formation 44 is configured as a socket for receiving complementary formations which are connected to nose piece 150 as discussed below. The headgear may be provided with a pair of seal rings 46.1, each joined to the headgear at a respective aperture for establishing a close seal with the nose-piece 150.

In the illustrated embodiment, the sheets 17 are flocked (e.g., have a velvet-like texture) to provide comfort to the patient, and their attachment to each other is reinforced by stitching 52 (see FIG. 1). The headgear 10 may also be provided with a cover (not shown) of cloth or other material which will be comfortable to a patient, and the cover may have decorative effects, e.g., patterns or other markings, which may be attractive to a child patient.

A thin layer of foam rubber or other suitable padding (not shown) may be provided in selected locations between the inner surfaces of the sheets 17 to enhance the structural integrity of the headgear 10, or otherwise improve comfort to the patient especially on the bony regions of the face, e.g., the cheekbones.

Referring now to FIG. 4, the nose piece 150 is discussed in more detail. The nose piece 150 includes a conduit 152 having outer walls 154. The outer walls 154, in turn, are double walls, having inner wall portions 156 and outer wall portions 158. The inner wall portions 156 and outer wall portions 158 are sealingly joined to each other at first and second ends 160 and 162, respectively, of the nose piece 150. Each end 160 and 162 is configured for connection in fluid flow communication to the portion 46 of a respective nose attachment formation 44.

The inner wall portions 156 and outer wall portions 158 define, between them, an annular space 164 extending circumferentially with respect to the nose piece 150.

The conduit 152 defines a pair of apertures 166 each for accommodating a respective nostril formation 168 of flexible plastic or elastomer (e.g., silicone rubber) which extends through the relevant aperture 166. Each nostril formation 168 has a central passage 170. The nostril formations 168 are shaped to provide a close comfortable fit in the patient's nose 42, i.e., in the patient's nostrils. The nostril formations 168 may have any suitable form, e.g., nasal pillows, nasal prongs, cannula, or nasal puffs. If desired, the nostril formations 168 may be shaped and sized so as to be customized to a particular patient's nose.

The outer walls 154 of the nose piece 150 define a central passage 172 for establishing fluid flow communication between the interiors of the conduits 12 and passages 170 of the nostril formations 168, and hence with the patient's nose 42.

Similar to the headgear 10, the conduit 152 may be formed from sheets of polymeric (e.g., plastic) material which may be suitably joined by I-IF plastics welding to achieve the construction represented in FIG. 4.

Opening through the outer wall portion 158 of each nose piece 150, into the respective annular space 164, is an inflation nipple 175 having a one-way valve 174 which is illustrated in more detail in FIGS. 9 and 9A. The nipple 175 and one-way valve 174 permit the introduction of air into the annular space 164 so as to inflate the conduit 152 to provide it with sufficient rigidity to maintain its shape, while not depriving it of sufficient flexibility so as to be uncomfortable to the patient. The nipple 175 and valve 174 can thus be used to introduce more air into, or to remove air from, the annular space 164 so as to allow the rigidity or size of the conduit 152 to be adjusted to suit a particular patient or particular circumstances.

The nipple 175 may include a short tube 302. The nipple 175 includes a base 304 below the short tube 302, the base being joined, e.g., by plastics welding, to the nose piece 150 (or to the headgear 10 in the case of the headgear 10 being inflatable). The plastic material of the base 304 may be thinner than that of the remainder of the tube structure 300. This allows for twisting of the short tube 302 as represented in phantom lines, and by the arrow 305, in FIG. 9. The base 304 also is near the one way valve 174 as described below.

The nipple 175 also includes a cap 306 receivable as a tight but removable fit in the short tube 302 for closing off the short tube 302 and preventing the passage of air through it. As illustrated, a flexible cord 308 joins the cap 306 to an upper side position of the short tube 302. The flexibility of the cord 308 allows the cap 306 to be moved between its closure condition as shown in which it closes the short tube 302, and an open condition in which it is removed from the opening of the short tube 302.

The nipple 175 is also provided with an upper waist region 310 and a lower waist region 312 which is narrower that the upper waist region 310. These waist regions allow deformation of the nipple 175 by permitting the lower waist region 312 to be telescopically received within the upper waist region 310. This, in turn, allows the nipple 175 to be pressed into that portion of the nose piece 150 (or headgear 10 if the headgear 10 is inflatable) to which it is joined so that it becomes inverted within that portion, and effectively stowed away.

As described above, the base 304 of the nipple 175 is near the one way valve 174, which has a moveable flap 174.1. The moveable flap 174.1 extends from and is hinged to, and formed integrally with, the internal wall of short tube 302. The one way valve 174 includes a flange 174.4 which serves the purposes of a detent to prevent the flap 174.1 moving past the flange 174.4 in the direction of arrow 174.2, when the cavity 174.5 is under pressure. The flange 174.4 also provides a location for the edge of the flap 174.1 to seal against.

When the cavity 174.6 has a greater pressure therein than the cavity 174.5, e.g., when it is being inflated, the flap 174.1 will move in the direction of arrow 174.3 allowing inflation. As soon as there is a pressure differential, the flap 174.1 will move to a closed position, thereby acting as a one way valve. To deflate via the nipple 175, the user need only deform nipple 175 by compressing or squeezing the sides in the region of the one way valve 174, whereby the deformation will break the seal with the flange 174.4 allowing deflation.

In another embodiment, the nostril formations 168, instead of being separate formations of rigid plastic, may be integral with the conduit 152. In such an embodiment, the apertures 166 may be omitted.

In one form of this embodiment, the nostril formations 168 may have outer wall portions and inner wall portions which may be continuous with the outer wall portions 158 and inner wall portions 156, respectively, of the conduit 152, and which define between them a space which may be continuous with the annular space 164. Thus, inflation of the conduit 152 may also cause inflation of the nostril formations 168.

In a further embodiment as shown in FIG. 3, the nose piece 150 may be integral with the conduits 12 so that the headgear 10 and conduit 152 are of a unitary construction. In one form of this embodiment, the nostril formations 168 may be rigid plastics formations received in apertures 166 of the conduit 152. In another form of this embodiment, the nostril formations 168 may be integral and continuous with the conduit 152 as described above.

In another embodiment as shown in FIG. 5, instead of having a nose piece which includes a conduit such as the conduit 152 and nostril formations such as the nostril formations 168, two inflatable curved nostril formations 176 (only one being shown) may be provided. In the illustrated embodiment, each nostril formation 176 has outer wall portions 178 and inner wall portions 180 defining a central enclosed annular space 182 between them, a one-way valve 184 for introducing air to the space 182 to inflate the nostril formation 176, and a central passage 186. In this embodiment, one end 188 of each nostril formation 176 is configured for attachment to the portion 46 of a respective nose attachment formation 44, while an opposite end 190 is configured for being received in the patient's nose 42. In an embodiment, the nostril formations 176 for each of the patient's two nostrils may be adapted to be attached to each other, to facilitate support of the nostril formations 176 and their sealing with the patient's nose.

In other embodiments, the nose pieces 150 or conduits 152 thereof may be other than the inflatable constructions as described above. They may, instead, have single outer walls of similar construction to the conduits 12.

For example, the nasal interface may be structured similar to nasal assemblies disclosed in U.S. Pat. No. 10,781,929, which is incorporated herein by reference in its entirety.

Alternatively, the conduits 12, instead of having their walls formed of single plastic sheets as described above, may be made up of double walls having inner wall portions and outer wall portions similar to the inner wall portions 156 and outer wall portions 158, respectively, of the nose piece 150. These inner and outer wall portions would define a sealed and inflatable inner space similar to the space 164 of the nose pieces 150.

This construction of double walls may be used for the whole of the headgear 10, or selected portions of it. This would enable selected portions of the headgear 10, which are inflatable as a result of the double wall construction, to be inflatable as in the case of the conduits 152 of the nose piece 150, to achieve a desired amount of rigidity where required. The double wall construction would also serve to reduce noise transferred through the walls.

In one embodiment, an inner skeleton may be provided in some or all parts of the above equipment where such double walls are provided in the cavity between the relevant inner and outer wall portions. The inner skeleton may be comprised, for example, of spring wire, and this could be configured in an expanded condition to provide further structural support where the skeleton is used.

In use, as described in relation to FIG. 1, the headgear 10 is placed on the head 34 of the patient. The T-connection 20 is connected to a supply pipe (not shown) of an air supply (also not shown) configured for supplying air under a positive pressure. The supply pipe will include an end for attachment to the attachment formation 30 for effecting a seal with the T-connection 20.

In another embodiment or in combination with the embodiment described above, a suitable structure may be provided for minimizing the extent to which the supply pipe pulls on the headgear 10. This structure may involve a pivotable pipe connection, a ball-and-socket connection, or a flexible bellows connection (such as that described in the next paragraph) to the T-connection 20, or to another part 290 (FIG. 12) of the relevant headgear in an embodiment where there is no such T-connection. This may facilitate stability of the headgear 10 by reducing the extent to which drag forces on the supply pipe are transferred to the headgear 10.

The attachment formation 30 may include a concertina tube 300 as illustrated in FIG. 10, which terminates in a cylindrical union 32. The tube 300 may allow for relative rotation of the air supply coupling thereby preventing the transfer of bending forces which would otherwise uncouple the air supply connection.

The supplied air passes into the central pipe 24 of the T-connection 20 and then via the side pipes 22 into the conduits 12. As the air is under a positive pressure, it serves to inflate the conduits 12 so that they define central passages extending from their respective first ends 28 to their respective second ends 40. The air then passes via the nose attachment formations 44 and nose piece 150, into the patient's nose 42 (i.e., the nostrils).

The headgear 10 may be custom fit to a particular patient's head 34. This may be achieved by scanning or mapping the head 34 to determine its shape in a three-dimensional sense, and then cutting the sheets 17 so that when the sheets 17 are joined to each other they form a headgear 10 which is suitable for achieving a close and comfortable fit on the patient's head 34. It will be appreciated that there may be as many different shapes of the headgear 10 as there are patient's heads 34. In addition, once a particular shape is determined in which to form a sheet 17 in relation to a particular patient's head, or in relation to a particular type of head shape (which may apply to more than one patient), there is no limitation on the number of sheets that may be cut to a particular sheet shape to form a particular headgear.

In an embodiment, the sheets 17 may be joined along predetermined joint paths, In this regard, reference is made to the cushion 200 shown in FIGS. 7 and 8, which has two sheets 202 (only one being shown) joined along paths 204. It will be seen that the paths 204 are of a sinusoidal, zig-zag shape with peaks 206 and troughs 208 such as may be found in quilting-like formations. The troughs 208 of each path 204 are aligned with the peaks 206 of the next path and vice versa, so as to form substantially diamond-shaped areas 210 between the paths where the sheets 202 are not connected to each other. In an embodiment of the headgear 10 under discussion, the headgear 10 may be formed with the sheets 17 being joined to each other in a similar fashion to the sheets 202, with the paths serving as fold lines to facilitate curving of the joined sheets 17 (as represented by the curving of the cushion 200 in FIG. 8) to conform to the shape of the head 34.

The regions of the headgear 10 corresponding to the diamond-shaped areas 210 of the cushion 200 may be inflated to form a number of juxtaposed cushioned zones to provide added comfort to the patient and to facilitate the firm and even seating of the headgear 10 on the patient's head 34.

Alternatively, instead of using the mapping to determine the shape in which the sheets 17 are to be cut as described above, the mapping may be used to form part of a headgear by forming a thermoplastic polymer in the shape of the patient's head 34.

The shaping of the headgear 10 to suit the particular shape of a patient's head 34 may significantly assist in achieving a headgear 10 having conduits 12, a central portion 14, and a strap 16 which are snugly fitted to the patient's head 34. This may achieve an effective distribution of pressure between the headgear 10 and the patient's head 34 rather than having specific locations at which there are high pressure points and other locations at which there is insufficient pressure. This, in turn, facilitates the secure attachment of the headgear 10 to the patient's head 34.

In addition, the unitary construction of the conduit 12, central portion 14 and strap 16, with the headgear 10 being specifically suited to a particular patient's head 34, eliminates the need for adjustment parts of the headgear 10 which would otherwise be required to fasten the headgear 10 securely to the patient's head 34. This unitary construction also simplifies the donning of the headgear 10 and removal thereof from the patient's head.

The snug securing of the headgear 10 to the patient's head 34 may be further facilitated in those embodiments of the headgear 10 having double walls, or portions with double walls as referred to above. In these embodiments, inflation of the double walls (i.e., provision of inflating air into the space between the double walls) causes the respective inner wall portions to press more firmly against the patient's head 34. This can be particularly useful in relation to those parts of the patient's head 34 which are of a substantially concave or recessed shape, such as immediately in front of the patient's ears 38.

With the nose piece 150 being joined to the conduits 12 as described above, the air supplied into the center pipe 24 of the T-connection 20, after having passed through the passages of the conduits 12, proceeds to pass along the passage 166 of the conduit 152 of the nose piece 150, and into the patient's nose 42.

Exhalation by the patient is facilitated by using a material for the plastic sheets 17 which is to some extent gas permeable, preferably in the vicinity of the nose 42 of the patient. This will allow for a certain amount of leakage or venting of air and exhaled carbon dioxide therethrough. A suitable thermoplastic elastomer, e.g., a poly-olefin, may be used for this purpose. Alternatively, the sheets 17, instead of being fully of plastic, may be wholly, or may have parts, made of other types of gas permeable material, e.g., silk or other woven material, or the Polytetrafluoroethylene (PTFE) material known as GORETEX®.

As the patient breathes out, the exhaled breath can then pass via the nose pieces 150 and then through the walls of the conduits 12 at positions close to the respective second ends 40 thereof.

A particularly suitable material for the sheets may be breathable polyurethane which allows the passage of water vapour with the escaping air, but provides a substantially airtight passage. By the expression “substantially airtight,” it is meant that sufficient resistance to the passage of air therethrough is provided to prevent too much air from escaping. The ability to allow water vapour to pass through is advantageous as it may assist in avoiding an undesirable accumulation of moisture originating from gases exhaled by the patient, in the interior passages of the conduits 12. Materials that may provide these properties include those manufactured by the Darlington Corporation known by the trademark DARLEXX®, or the 3M product known by the trademark THINSULATE®, or the Polytetrafluoroethylene (PTFE) material known as GORETEX®, or the product known as ATLANTECH™ made by Atlantis Weather Gear Inc.

With the walls of the conduits 12, or parts thereof, being gas permeable as described above, some of the air supplied via the center pipe 24 of the T-connection 20 will also escape from the conduits 12. This arrangement and the flexible nature of the passageways can assist in a reduction in the noise generated by the passage of air via the conduit 12 to the nose pieces 150.

The passage of exhaled gas through the walls of the conduits 12 may also provide a useful means for allowing heat to escape from the headgear 10. Such heat, if not allowed to escape in this manner, may result in the headgear 10 becoming so heated as to be unnecessarily uncomfortable for the patient. In addition, the gas permeability of the materials used, as referred to above, may permit the passage of heat and water vapour through the parts of the headgear on top of the patient's head 34 to improve comfort, especially in warmer weather. The construction of the headgear 10, and particularly its unitary nature, has the advantage that, if the headgear 10 is being worn by the patient, and the patient rolls his or her head 34 onto a surface such as a pillow so that one of the conduits 12 is flattened by the pressure of the patient's head 34 on the pillow, all or most of the air that would have passed through that conduit 12 but which is prevented from doing so due to the constriction of the conduit's passage is permitted to pass instead through the other conduit 12. This is enabled due to the flexibility of the conduits 12 and their resultant ability to expand and substantially collapse. Thus, the total volume flow rate of the air through the pair of conduits remains substantially constant during the flattening and expansion of the respective conduits. Depending on the configuration and cross-sectional shapes of the conduits 12 when the above flattening and expansion occurs, the collapsing of the conduit 12 causes a change in the ratio between a height extent and a lateral extent of that conduit, with the height extent decreasing and the lateral extent increasing. Similarly, the deformation of the other conduit causes a change in the ratio between its height extent and lateral extent with the height extent increasing and the lateral extent decreasing.

In an embodiment, the headgear may include an adjustable head cap with the conduits being attached to the cap at opposite sides thereof. In this case, the cap may constitute the attachment means, and the connection means may be mounted on the cap.

In another embodiment, the conduits may be detachable from the attachment means so that the attachment means may be selectively releasably connected with differently sized and/or shaped conduits. In this case, the conduits may be selectively releasably connected with differently sized and/or shaped attachment means, whereby the headgear may form part of a modular headgear system having interchangeable attachment means and conduits.

In yet another embodiment, the headgear may be adapted for use with a patient mask, the mask being configured to fit the patient's head adjacent the patient's nose to direct gas from the conduits to the nose. Then, the headgear may be adapted to be detachable from the mask to enable the patient to selectively remove the mask from the headgear and hence from the patient's head while the headgear continues to be being worn by the patient.

A particular advantage of the headgear 10 as described is that, when not in use, the T-connection 20 may be removed from the aperture 18. Then, the conduit 12, the central portion 14, and the strap 16 may be flattened out so as to collapse the passages of the conduits 12, and rolled up or folded for storage purposes, so that a minimum of storage room is required. On the other hand, when in use, the passage of air itself through the conduits 12 serves to inflate the passages and to press the inside walls of the conduits 12 firmly against the sides of the patient's head 34 to achieve a comfortable and snug fit.

The headgear 10 has various advantages. For example, an advantage of the headgear 10 is that the T-connection 20 is located in use at a position of the patient's head which is unlikely to be subjected to any compression force due, for example, to the patient's head being on a pillow. Thus, while the conduits 12 are flexible and should therefore not provide much discomfort to the patient even if the patient lies on them, this should not be an issue in respect of the relatively hard T-connection 20, due to the location of this component.

In addition, the relative flexibility and hence softness of the material from which the conduits 12, the central portion 14 and strap 16 are formed allows the headgear 10 to be engaged with parts of the patient's head, such as the patient's cheeks, that may have been too sensitive for engagement with prior art devices.

The fact that the conduits 12 and central portion 14 define most of the passageways through which air needs to travel to be delivered to the patient means that the need for additional tubing and tubing securement straps may be avoided. Therefore, this also avoids the bulk and weight that such additional tubing and securement straps might involve.

The ability of one of the conduits 12 to expand to allow for a greater volume flow rate when the other conduit 12 is compressed or collapsed so as to be generally flat against the patient's face (e.g., when the patient lies on the other conduit 12 on a pillow) enhances the patient's comfort and minimizes discomfort that might have been caused if more inflexible tubing were used. It also reduces discomfort that may be caused by engagement of the headgear 10 with contact pressure points on the patient's head 34.

The use of plastics welding as described above for manufacturing the headgear 10 avoids the need for clips, buckles, adjustment straps and the like, thus providing for greater simplicity of use. In addition, the forming of the headgear 10 to suit the shape of the patient's head 34 and the inherent lightweight nature of the headgear 10 assists in providing greater comfort to the patient.

Referring to FIG. 6, there is shown a schematic representation of a PAP machine conduit 400 according to an embodiment of the invention. The conduit 400 has flexible conduit walls 402, and has a first end 404 and a second end 406. The first end 404 is attached to a supply means 408 for supplying air under a positive pressure. As in the case of the conduits 12 described above, the conduit 400 is collapsible. As air under a positive pressure is supplied by the supply means 408, the pressure of the air urges the walls 402 into the condition shown, in which the walls 402 define a central passage 410 of the conduit 400. Thus, the air may pass along the passage 410 to the second end 406, where the air may be directed as required.

As an alternative to the walls 402 being urged into the condition shown only by the pressure of the air, a collapsible spring may be provided which assists in preventing kinking of the conduit 400 in use.

The flexibility of the walls 402 allows the conduit 400 to be folded or rolled to a compact size during storage or travel. In addition, these walls may be of a single wall type or a double wall type similar to the walls 154 described above. Such a double wall construction may also provide enhanced insulation to assist in regulating the temperature of the air from the air supply means 408.

Illustrated in FIG. 11 is headgear 1010, which is similar to the headgear 10 of FIGS. 1 and 2, and accordingly, like parts have been like numbered. The headgear 1010 differs from the headgear 10 in that two straps 1012 are provided, each of which is connected to and extends from a respective one of the conduits or side portions 12 of the headgear 10. The straps 1012 respectively terminate in buckle members 1014 and 1016 which can connect to a mask or nose piece and allow a user to secure the headgear 1010 to his or her head. The straps 1012 may provide for adjustability of the strap length.

Illustrated in FIG. 12 is headgear 1110, which is similar to the headgear 10 of FIGS. 1 and 2, and accordingly, like parts have been like numbered. The headgear 1110 differs from the headgear 10 in that a collapsible cuff 1112 is provided on ends of each of the conduits or side portions 12. As illustrated, the collapsible cuff 1112 is of a bellows formation. The collapsible cuff 1112 allows the length of the ends of the conduits 12 to be adjusted by extension or contraction, as required.

It will be understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text. All of these different combinations constitute various alternative aspects of the invention.

While the invention has been described in connection with what are presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. In addition, while the invention has particular application to patients who suffer from OSA, it is to be appreciated that patients who suffer from other illnesses (e.g., congestive heart failure, diabetes, morbid obesity, stroke, barriatric surgery, etc.) can derive benefit from the above teachings. Moreover, the above teachings have applicability with patients and non-patients alike. 

1-10. (canceled)
 11. An assembly for delivering a supply of pressurized gas to a patient for treatment of sleep disordered breathing, the assembly comprising: an interface configured to engage the patient's face to direct the supply of pressurized gas to an airway of the patient; and headgear to support the interface in a desired position on the patient's face, the headgear including: a pair of flexible conduits and a central portion disposed between and joining the pair of conduits, the central portion being adapted to be in fluid communication with an air supply tube arranged to deliver the supply of gas to the central portion, the central portion being configured to be positioned on top of and in contact with the patient's head when the assembly is worn; the pair of flexible conduits being configured to support the interface in a desired position on the patient's face and to deliver the supply of gas to the interface in use, each conduit having a top portion in fluid communication with the central portion and a bottom portion detachably connected to, and in fluid communication with, a lateral side of the interface, each conduit being arranged to, in use, extend along and engage a respective side of the patient's head between the patient's eye and ear; and a rear securement structure extending between the pair of flexible conduits and configured to engage a rear portion of the patient's head when the assembly is worn, wherein the conduits, the central portion and the interface form a ring with a ring-shaped gas passageway, wherein each conduit has an adjustable section along only a portion of the conduit, a length of the conduit being adjustable along the adjustable section thereby allowing a circumferential length of the ring to be adjusted when the assembly is donned so as to accommodate different patient head sizes, each adjustable section being arranged to directly contact the patient when the assembly is worn, and wherein the headgear does not include additional conduit tubing and does not include an additional securement structure beyond the rear securement structure.
 12. The assembly according to claim 11, wherein each adjustable section is configured to facilitate the length of the headgear being extended and contracted.
 13. The assembly according to claim 12, wherein each adjustable section comprises a flexible bellows.
 14. The assembly according to claim 11, further comprising an air connector removably attached to the headgear at the central portion and adapted to be connected to the air supply tube to deliver the supply of gas to the central portion, the air connector being configured to be positioned on top of the patient's head when the assembly is worn.
 15. The assembly according to claim 14, wherein the air connector enables movement of the air supply tube with respect to the central portion to reduce tube drag.
 16. The assembly according to claim 14, wherein the air connector comprises a swiveling device.
 17. The assembly according to claim 14, said central portion further comprising an aperture formed therein and adapted to be in fluid communication with the air supply tube, wherein an interior portion of the air connector extends into the aperture and an exterior portion of the air connector protrudes from the aperture.
 18. The assembly according to claim 11, wherein the central portion is integrally formed with the pair of conduits to join the top portions of the conduits, the central portion and pair of conduits forming a unitary construction.
 19. The assembly according to claim 18, wherein each adjustable section is respectively positioned along a portion of the corresponding conduit between the bottom portion of the conduit and the central portion of the headgear.
 20. The assembly according to claim 19, wherein each adjustable section is respectively positioned along a portion of the corresponding conduit proximate and end of the conduit.
 21. The assembly according to claim 20, wherein the end of the conduit is at the bottom portion.
 22. The assembly according to claim 11, wherein each conduit comprises a conduit wall that is deformable between (a) an open condition in which the conduit wall defines a conduit passage along which the pressurized gas can travel from the top portion to the bottom portion, and (b) a collapsed condition in which the conduit wall collapses the conduit passage resulting, in use, in a decrease in volume flow rate through the conduit passage.
 23. The assembly according to claim 22, wherein each conduit is configured to, in use, deform into the collapsed condition under the weight of the patient's head.
 24. The assembly according to claim 23, wherein the adjustable section of each conduit is configured to deform into the collapsed condition under the weight of the patient's head.
 25. The assembly according to claim 11, wherein the rear securement structure is configured to the pair of flexible conduits at a fixed connection point along the length of each conduit.
 26. The assembly according to claim 25, wherein the connection points are arranged to be positioned superior to the patient's ears when the assembly is worn.
 27. The assembly according to claim 25, wherein the rear securement structure connects directly to the pair of flexible conduits.
 28. The assembly according to claim 27, wherein the rear securement structure is a strap.
 29. The assembly of claim 11, further comprising: an interface connector attached to the bottom portion of each conduit, each interface connector being removably connected to a respective lateral side of the interface; and a vent in the vicinity of the patient's nose to allow exhaled carbon dioxide to pass to atmosphere.
 30. The assembly according to claim 11, further comprising: an air connector removably attached to the headgear at the central portion and adapted to be connected to the air supply tube to deliver the supply of gas to the central portion, the air connector being configured to be positioned on top of the patient's head when the assembly is worn; and further comprising an interface connector attached to the bottom portion of each conduit, each interface connector being removably connected to a respective lateral side of the interface, said central portion further comprising an aperture formed therein and adapted to be in fluid communication with the air supply tube, an interior portion of the air connector extends into the aperture and an exterior portion of the air connector protrudes from the aperture, wherein the central portion is integrally formed with the pair of conduits to join the top portions of the conduits, the central portion and pair of conduits forming a unitary construction, wherein each adjustable section is configured to facilitate the length of the headgear being extended and contracted, wherein each adjustable section comprises a flexible bellows, wherein each conduit comprises a conduit wall that is deformable between (a) an open condition in which the conduit wall defines a conduit passage along which the pressurized gas can travel from the top portion to the bottom portion, and (b) a collapsed condition in which the conduit wall collapses the conduit passage resulting, in use, in a decrease in volume flow rate through the conduit passage, and wherein each conduit is configured to, in use, deform into the collapsed condition under the weight of the patient's head, the adjustable section of each conduit being configured to deform into the collapsed condition under the weight of the patient's head.
 31. A positive air pressure system for treatment of sleep disordered breathing, comprising: a flow generator to provide a supply of pressurized gas; the assembly of claim 11; and an air supply tube fluidly connecting the flow generator and the patient interface assembly.
 32. An assembly for delivering a supply of pressurized gas to a patient for treatment of sleep disordered breathing, the assembly comprising: an interface configured to engage the patient's face to direct the supply of pressurized gas to an airway of the patient; and headgear to support the interface in a desired position on the patient's face, the headgear including: a pair of flexible conduits and a central portion disposed between and joining the pair of conduits, the central portion being adapted to be in fluid communication with an air supply tube arranged to deliver the supply of gas to the central portion, the central portion being configured to be positioned on top of and in contact with the patient's head when the assembly is worn; the pair of flexible conduits being configured to support the interface in a desired position on the patient's face and to deliver the supply of gas to the interface in use, each conduit having a top portion in fluid communication with the central portion and a bottom portion detachably connected to, and in fluid communication with, a lateral side of the interface, each conduit being arranged to, in use, extend along a respective side of the patient's head between the patient's eye and ear, wherein the conduits, the central portion and the interface form a ring with a ring-shaped gas passageway, wherein each conduit has an adjustable section along only a portion of the conduit, a length of the conduit being adjustable along the adjustable section thereby allowing a circumferential length of the ring to be adjusted when the assembly is donned so as to accommodate different patient head sizes, wherein each adjustable section has opposing first and second ends in a direction along the length of the respective conduit, the first end of each adjustable section being relatively proximal the top portion of each respective conduit as compared to the second end of each corresponding adjustable section, the second end of each adjustable section being relatively proximal the bottom portion of each respective conduit as compared to the first end of each corresponding adjustable section, and wherein a width of each conduit at the first end of each respective adjustable section is larger than a width of the conduit at the second end of the adjustable section.
 33. The assembly according to claim 32, wherein the width of each conduit along the adjustable section tapers towards the bottom portion of the conduit.
 34. The assembly according to claim 33, wherein the width of each conduit along the adjustable section tapers towards the bottom portion along an entire length of the adjustable section.
 35. The assembly according to claim 34, wherein each adjustable section is configured to facilitate the length of the headgear being extended and contracted.
 36. The assembly according to claim 35, wherein each adjustable section comprises a flexible bellows.
 37. The assembly according to claim 32, further comprising an air connector removably attached to the headgear at the central portion and adapted to be connected to the air supply tube to deliver the supply of gas to the central portion, the air connector being configured to be positioned on top of the patient's head when the assembly is worn, wherein the central portion is integrally formed with the pair of conduits to join the top portions of the conduits, the central portion and pair of conduits forming a unitary construction.
 38. The assembly according to claim 37, said central portion further comprising an aperture formed therein and adapted to be in fluid communication with the air supply tube, wherein an interior portion of the air connector extends into the aperture and an exterior portion of the air connector protrudes from the aperture.
 39. An assembly for providing respiratory therapy to a patient, the assembly comprising: an interface configured to deliver a flow of pressurized breathable gas to an airway of the patient; a pair of flexible conduits configured to support the interface and to deliver the flow of pressurized breathable gas to the interface, wherein the pair of flexible conduits are joined at a central portion that is fluidly connected to a shared inlet through which the flow of pressurized breathable gas is received into the pair of flexible conduits, wherein the pair of flexible conduits have longitudinal lengths that extend from the central portion to interface connectors configured to be fluidly connected to opposing sides of the interface, wherein the central portion is spaced apart from the interface such that, during delivery of the flow of pressurized breathable gas to the interface, the central portion is retained in a mounting position on a top of the patient's head by the pair of flexible conduits extending along opposing sides of the patient's head between the patient's eye and ear on each respective side, wherein the pair of flexible conduits include length adjustable structures along only a portion of the pair of flexible conduits that provide adjustability of the longitudinal lengths of the pair of flexible conduits, wherein the length adjustable structures have elasticity that permits resilient extension and contraction of the pair of flexible conduits to snugly fit the patient's head while retaining the interface in the mounting position to deliver the flow of pressurized breathable gas to the airway of the patient; and a rear strap configured to extend between the pair of flexible conduits and around only a portion of a circumference of the patient's head that is posterior an apex of the patient's head, wherein the rear strap is configured to connect to the pair of flexible conduits at fixed locations along the length of the pair of flexible conduits that, during delivery of the flow of pressurized breathable gas to the interface, are between (i) the central portion at the top of the patient's head and (ii) an axial plane at a top of the patient's ears, wherein the central portion, at its fluid connection to the inlet, is wider than adjacent portions of the pair of flexible conduits that are adjacent and connected to the central portion, the adjacent portions of the pair of flexible conduits being configured to be retained on top of the patient's head in the mounting position, and wherein, during delivery of the flow of pressurized breathable gas to the interface, the central portion and the adjacent portions contact the top of the patient's head such that an area of contact for the central portion is wider along a sagittal plane than areas of contact for the adjacent portions, and wherein the assembly does not include additional securement straps beyond the pair of flexible conduits and the rear strap.
 40. The assembly according to claim 39, wherein the length adjustable structures are positioned along the pair of flexible conduits between the central portion and the interface connectors, wherein the elasticity of the length adjustable structures is configured to resiliently contract and extend the longitudinal lengths of the pair of flexible conduits to snugly fit the patient's head, and wherein the length adjustable structures comprise bellows formations. 